Emission Spectroscopy-Based Sensor System to Correlate the In-Cylinder Combustion Temperature of a Diesel Engine to NOx Emissions.

Due to a rising importance of the reduction of pollutant, produced by conventional energy technologies, the knowledge of pollutant forming processes during a combustion is of great interest. In this study the in-cylinder temperature, of a near series diesel engine, is examined with a minimal invasive emission spectroscopy sensor. The soot, nearly a black body radiator, emits light, which is spectrally detected and evaluated with a modified function of Planck's law. The results show a good correlation between the determined temperatures and the NOx concentration, measured in the exhaust gas of the engine, during a variety of engine operating points. A standard deviation between 25 K and 49 K was obtained for the in-cylinder temperature measurements.

The atypical IκB family member Bcl3 determines differentiation and fate of intestinal RORγt+ regulatory T-cell subsets.

Peripherally-induced regulatory T cells (pTregs) expressing the retinoic acid receptor-related orphan-receptor gamma t (RORγt) are indispensable for intestinal immune homeostasis. Nuclear factor kappa family members regulate the differentiation of thymic Tregs and promote their survival in the periphery. However, the Treg intrinsic molecular mechanisms controlling the size of the pTregs in the intestine and associated lymphoid organs remain unclear. Here, we provide direct evidence that B-cell lymphoma 3 (Bcl3) limits the development of pTregs in a T cell-intrinsic manner. Moreover, the absence of Bcl3 allowed for the formation of an unusual intestinal Treg population co-expressing the transcription factors Helios and RORγt. The expanded RORγt+ Treg populations in the absence of Bcl3 displayed an activated phenotype and secreted high levels of the anti-inflammatory cytokines interleukin (IL)-10 and transforming growth factor beta. They were fully capable of suppressing effector T cells in a transfer colitis model despite an intrinsic bias to trans-differentiate toward T helper 17-like cells. Finally, we provide a Bcl3-dependent gene signature in pTregs including altered responsiveness to the cytokines IL-2, IL-6, and tumor necrosis factor alpha. Our results demonstrate that Bcl3 acts as a molecular switch to limit the expansion of different intestinal Treg subsets and may thus serve as a novel therapeutic target for inflammatory bowel disease by restoring intestinal immune tolerance.

Unrestrained cleavage of Roquin-1 by MALT1 induces spontaneous T cell activation and the development of autoimmunity.

Constitutive activation of the MALT1 paracaspase in conventional T cells of Malt1TBM/TBM (TRAF6 Binding Mutant = TBM) mice causes fatal inflammation and autoimmunity, but the involved targets and underlying molecular mechanisms are unknown. We genetically rendered a single MALT1 substrate, the RNA-binding protein (RBP) Roquin-1, insensitive to MALT1 cleavage. These Rc3h1Mins/Mins mice showed normal immune homeostasis. Combining Rc3h1Mins/Mins alleles with those encoding for constitutively active MALT1 (TBM) prevented spontaneous T cell activation and restored viability of Malt1TBM/TBM mice. Mechanistically, we show how antigen/MHC recognition is translated by MALT1 into Roquin cleavage and derepression of Roquin targets. Increasing T cell receptor (TCR) signals inactivated Roquin more effectively, and only high TCR strength enabled derepression of high-affinity targets to promote Th17 differentiation. Induction of experimental autoimmune encephalomyelitis (EAE) revealed increased cleavage of Roquin-1 in disease-associated Th17 compared to Th1 cells in the CNS. T cells from Rc3h1Mins/Mins mice did not efficiently induce the high-affinity Roquin-1 target IκBNS in response to TCR stimulation, showed reduced Th17 differentiation, and Rc3h1Mins/Mins mice were protected from EAE. These data demonstrate how TCR signaling and MALT1 activation utilize graded cleavage of Roquin to differentially regulate target mRNAs that control T cell activation and differentiation as well as the development of autoimmunity.

An innate immune sensor wandering around - NOD1 promotes cell migration via non-canonical signaling.

NOD1 is a cytosolic immune receptor well known for recognizing intracellular bacteria and inducing innate immune responses. Upon ligand binding, it usually forms a complex with the serine/threonine kinase RIPK2 to activate the transcription factor NF-κB. Next to its role in pathogen recognition, NOD1 has been associated with cancer progression. In this regard, Hezinger et al. investigated a non-canonical role of NOD1 in cell migration. They discovered that NOD1 is crucial for the migration and chemotaxis of HeLa cells and identified HAX-1 as a novel interaction partner.

Immunophenotyping of Monocyte Migration Markers and Therapeutic Effects of Selenium on IL-6 and IL-1ß Cytokine Axes of Blood Mononuclear Cells in Preoperative and Postoperative Coronary Artery Disease Patients.

Multivessel coronary artery disease (CAD) is characterized by underlying chronic vascular inflammation and occlusion in the coronary arteries, where these patients undergo coronary artery bypass grafting (CABG). Since post-cardiotomy inflammation is a well known phenomenon after CABG, attenuation of this inflammation is required to reduce perioperative morbidity and mortality. In this study, we aimed to phenotype circulating frequencies and intensities of monocyte subsets and monocyte migration markers, respectively, and to investigate the plasma level of inflammatory cytokines and chemokines between preoperative and postoperative CAD patients and later, to intervene the inflammation with sodium selenite. We found a higher amplitude of inflammation, postoperatively, in terms of CCR1high monocytes and significantly increased pro-inflammatory cytokines, IL-6, IL-8, and IL-1RA. Further, in vitro intervention with selenium displayed mitigating effects on the IL-6/STAT-3 axis of mononuclear cells derived from postoperative CAD patients. In addition, in vitro selenium intervention significantly reduced IL-1ß production as well as decreased cleaved caspase-1 (p20) activity by preoperative (when stimulated) as well as postoperative CAD mononuclear cells. Though TNF-α exhibited a positive correlation with blood troponin levels in postoperative CAD patients, there was no obvious effect of selenium on the TNF-α/NF-κB axis. In conclusion, anti-inflammatory selenium might be utilized to impede systemic inflammatory cytokine axes to circumvent aggravating atherosclerosis and further damage to the autologous bypass grafts during the post-surgical period.

Preserved T-cell response in anti-CD20-treated multiple sclerosis patients following SARS-CoV-2 vaccination.

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has tremendous implications for the management of patients with autoimmune conditions such as multiple sclerosis (MS) under immune therapies targeting CD20+ B cells (aCD20). Objectives: Here, we investigated humoral and cellular immune responses, including anti-spike titers, neutralization against SARS-CoV-2 wild-type (WT), delta, and omicron variant and T cell responses of aCD20-treated relapsing-remitting MS patients following SARS-CoV-2 vaccination compared with healthy controls. Methods: Blood samples were collected within 4-8 weeks following the second vaccination against SARS-CoV-2. Sera were analyzed for anti-SARS-CoV-2 spike antibodies and neutralization capacity against pseudovirus for wild-type (WT), delta, and omicron variant. Peripheral blood mononuclear cells (PBMCs) were stimulated with a SARS-CoV-2 peptide pool and analyzed via flow cytometry. Results: The aCD20-treated MS patients had lower anti-SARS-CoV-2-spike titers, which correlated with B cell repopulation. Sera of aCD20-treated patients had reduced capacity to neutralize WT, delta, and omicron pseudoviruses in vitro. On the contrary, PBMCs of aCD20-treated patients elicited higher frequencies of CD3+ T cells and CD4+ T cells and comparable response of cytotoxic T cells, while Th1 response was reduced following restimulation with SARS-CoV-2. Conclusion: In summary, aCD20-treated patients have a reduced humoral immune response, depending on B cell repopulation, in accordance with preserved cellular immune response, suggesting partial cellular protection against SARS-CoV-2.

Impact of SARS-CoV-2 vaccination on systemic immune responses in people living with HIV.

Despite the development of vaccines, which protect healthy people from severe and life-threatening Covid-19, the immunological responses of people with secondary immunodeficiencies to these vaccines remain incompletely understood. Here, we investigated the humoral and cellular immune responses elicited by mRNA-based SARS-CoV-2 vaccines in a cohort of people living with HIV (PLWH) receiving anti-retroviral therapy. While antibody responses in PLWH increased progressively after each vaccination, they were significantly reduced compared to the HIV-negative control group. This was particularly noteworthy for the Delta and Omicron variants. In contrast, CD4+ Th cell responses exhibited a vaccination-dependent increase, which was comparable in both groups. Interestingly, CD4+ T cell activation negatively correlated with the CD4 to CD8 ratio, indicating that low CD4+ T cell numbers do not necessarily interfere with cellular immune responses. Our data demonstrate that despite the lower CD4+ T cell counts SARS-CoV-2 vaccination results in potent cellular immune responses in PLWH. However, the reduced humoral response also provides strong evidence to consider PLWH as vulnerable group and suggests subsequent vaccinations being required to enhance their protection against COVID-19.

In silico predicted therapy against chronic Staphylococcus aureus infection leads to bacterial clearance in vivo.

Staphylococcus aureus can lead to chronic infections and abscesses in internal organs including kidneys, which are associated with the expansion of myeloid-derived suppressor cells (MDSCs) and their suppressive effect on T cells. Here, we developed a mathematical model of chronic S. aureus infection that incorporates the T-cell suppression by MDSCs and suggests therapeutic strategies for S. aureus clearance. A therapeutic protocol with heat-killed S. aureus (HKSA) was quantified in silico and tested in vivo. Contrary to the conventional administration of heat-killed bacteria as vaccination prior to infection, we administered HKSA as treatment in chronically infected hosts. Our treatment eliminated S. aureus in kidneys of all chronically S. aureus-infected mice, reduced MDSCs, and reversed T-cell dysfunction by inducing acute inflammation during ongoing, chronic infection. This study is a guideline for a treatment protocol against chronic S. aureus infection and renal abscesses by repurposing heat-killed treatments, directed by mathematical modeling.

Immune response in ofatumumab treated multiple sclerosis patients after SARS-CoV-2 vaccination.

Objective: The pandemic induced by SARS-CoV-2 has huge implications for patients with immunosuppression that is caused by disorders or specific treatments. Especially approaches targeting B cells via anti-CD20 therapy are associated with impaired humoral immune response but sustained cellular immunity. Ofatumumab is a human anti-CD20 directed antibody applied in low dosages subcutaneously, recently licensed for Multiple Sclerosis (MS). Effects of early ofatumumab treatment on alterations of immune cell composition and immune response towards SARS-CoV-2 are incompletely understood. Methods: We here investigated immune cell alterations in early ofatumumab (Ofa) treated patients and effects on humoral (titer, neutralization capacity against wild type, Delta and Omicron) and cellular immune responses in Ofa treated MS patients following a third vaccination against SARS-CoV-2 compared to healthy controls. Results: We show that a mean treatment duration of three months in the Ofa group led to near complete B cell depletion in line with altered composition of certain CD4+ T cell subpopulations such as enhanced frequencies of naive and a decrease of non-suppressive regulatory T cells (Tregs). Titer and neutralization capacity against SARS-CoV-2 variants was impaired while cellular immune response was sustained, characterized by a strong T helper 1 profile (Th1). Interpretation: In summary, low dosage ofatumumab treatment elicits sustained depletion of B cells in line with alterations of immune cells, mainly Tregs. This is associated with impaired humoral immune response towards SARS-CoV-2 vaccination but preserved, Th1 driven cellular immunity adding crucial information regarding early effects of low dosage anti-CD20 therapy on humoral and cellular immunity.

Type of PaperY192 within the SH2 Domain of Lck Regulates TCR Signaling Downstream of PLC-γ1 and Thymic Selection.

Signaling via the TCR, which is initiated by the Src-family tyrosine kinase Lck, is crucial for the determination of cell fates in the thymus. Because of its pivotal role, ablation of Lck results in a profound block of T-cell development. Here, we show that, in addition to its well-known function in the initiation of TCR signaling, Lck also acts at a more downstream level. This novel function of Lck is determined by the tyrosine residue (Y192) located in its SH2 domain. Thymocytes from knock-in mice expressing a phosphomimetic Y192E mutant of Lck initiate TCR signaling upon CD3 cross-linking up to the level of PLC-γ1 phosphorylation. However, the activation of downstream pathways including Ca2+ influx and phosphorylation of Erk1/2 are impaired. Accordingly, positive and negative selections are blocked in LckY192E knock-in mice. Collectively, our data indicate that Lck has a novel function downstream of PLCγ-1 in the regulation of thymocyte differentiation and selection.

Nfkbid Overexpression in Nonobese Diabetic Mice Elicits Complete Type 1 Diabetes Resistance in Part Associated with Enhanced Thymic Deletion of Pathogenic CD8 T Cells and Increased Numbers and Activity of Regulatory T Cells.

Type 1 diabetes (T1D) in both humans and NOD mice is caused by T cell-mediated autoimmune destruction of pancreatic ß cells. Increased frequency or activity of autoreactive T cells and failures of regulatory T cells (Tregs) to control these pathogenic effectors have both been implicated in T1D etiology. Due to the expression of MHC class I molecules on ß cells, CD8 T cells represent the ultimate effector population mediating T1D. Developing autoreactive CD8 T cells normally undergo extensive thymic negative selection, but this process is impaired in NOD mice and also likely T1D patients. Previous studies identified an allelic variant of Nfkbid, a NF-κB signal modulator, as a gene strongly contributing to defective thymic deletion of autoreactive CD8 T cells in NOD mice. These previous studies found ablation of Nfkbid in NOD mice using the clustered regularly interspaced short palindromic repeats system resulted in greater thymic deletion of pathogenic CD8 AI4 and NY8.3 TCR transgenic T cells but an unexpected acceleration of T1D onset. This acceleration was associated with reductions in the frequency of peripheral Tregs. In this article, we report transgenic overexpression of Nfkbid in NOD mice also paradoxically results in enhanced thymic deletion of autoreactive CD8 AI4 T cells. However, transgenic elevation of Nfkbid expression also increased the frequency and functional capacity of peripheral Tregs, in part contributing to the induction of complete T1D resistance. Thus, future identification of a pharmaceutical means to enhance Nfkbid expression might ultimately provide an effective T1D intervention approach.

Gadd45 Proteins in Immunity 2.0.

To protect the host against invading pathogens such as viruses, bacteria, and parasites as well as against tumor cells, the immune system of vertebrates has to distinguish between self and non-self, but also between harmless and dangerous. To do so, the immune system developed an innate and an adaptive branch that provide immediate and long-lasting protection, respectively. Furthermore, the immune system is composed of different cell types, which are specialized to combat different threats, and it is located at strategic locations to manage surveillance of the whole body. Therefore, immune cells need to communicate with each other. Growth arrest and DNA damage-inducible 45 (Gadd45) proteins are important components of intracellular signaling networks that convey messages from other cells in the receiving cell into biological responses. Within the 7 years that have passed since my first overview about Gadd45 proteins in the immune system, substantial progress has been made in our understanding of the immune system and with respect to Gadd45 proteins. Therefore, it is time for an update-Gadd45 proteins in immunity 2.0. In order to put Gadd45 proteins into the context of the immune system, I will first give a brief introduction into the immune system. Afterwards, I will give a brief introduction into Gadd45 proteins. For deeper insight, I refer to the other chapters of this book. The third section discusses the role of Gadd45 proteins in myeloid and lymphoid cells. The last two sections will be on the function of Gadd45 proteins in infection, autoimmunity, and tumor immunology.

IκBNS-deficiency protects mice from fatal Listeria monocytogenes infection by blunting pro-inflammatory signature in Ly6Chigh monocytes and preventing exaggerated innate immune responses.

IκB proteins regulate the inhibition and activation of NF-κB transcription factor complexes. While classical IκB proteins keep NF-κB complexes inactive in the cytoplasm, atypical IκB proteins act on activated NF-κB complexes located in the nucleus. Most of the knowledge regarding the function of IκB proteins has been collected in vitro, while far less is known regarding their impact on activation and regulation of immune responses during in vivo infections. Combining in vivo Listeria monocytogenes (Lm) infection with comparative ex vivo transcriptional profiling of the hepatic response to the pathogen we observed that in contrast to wild type mice that mounted a robust inflammatory response, IκBNS-deficiency was generally associated with a transcriptional repression of innate immune responses. Whole tissue transcriptomics revealed a pronounced IκBNS-dependent reduction of myeloid cell-associated transcripts in the liver together with an exceptionally high Nfkbid promoter activity uncovered in Ly6Chigh inflammatory monocytes prompted us to further characterize the specific contribution of IκBNS in the inflammatory response of monocytes to the infectious agent. Indeed, Ly6Chigh monocytes primed during Lm infection in the absence of IκBNS displayed a blunted response compared to wild type-derived Ly6Chigh monocytes as evidenced by the reduced early expression of hallmark transcripts of monocyte-driven inflammation such as Il6, Nos2 and Il1ß. Strikingly, altered monocyte activation in IκBNS-deficient mice was associated with an exceptional resistance against Lm infection and protection was associated with a strong reduction in immunopathology in Lm target organs. Of note, mice lacking IκBNS exclusively in myeloid cells failed to resist Lm infection, indicating that the observed effect was not monocyte intrinsic but monocyte extrinsic. While serum cytokine-profiling did not discover obvious differences between wild type and IκBNS -/- mice for most of the analyzed mediators, IL-10 was virtually undetectable in IκBNS-deficient mice, both in the steady state and following Lm infection. Together, we show here a crucial role for IκBNS during Lm infection with IκBNS-deficient mice showing an overall blunted pro-inflammatory immune response attributed to a reduced pro-inflammatory signature in Ly6Chigh monocytes. Reduced immunopathology and complete protection of mice against an otherwise fatal Lm infection identified IκBNS as molecular driver of inflammation in listeriosis.

In-depth analysis of T cell immunity and antibody responses in heterologous prime-boost-boost vaccine regimens against SARS-CoV-2 and Omicron variant.

With the emergence of novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Variants of Concern (VOCs), vaccination studies that elucidate the efficiency and effectiveness of a vaccination campaign are critical to assess the durability and the protective immunity provided by vaccines. SARS-CoV-2 vaccines have been found to induce robust humoral and cell-mediated immunity in individuals vaccinated with homologous vaccination regimens. Recent studies also suggest improved immune response against SARS-CoV-2 when heterologous vaccination strategies are employed. Yet, few data exist on the extent to which heterologous prime-boost-boost vaccinations with two different vaccine platforms have an impact on the T cell-mediated immune responses with a special emphasis on the currently dominantly circulating Omicron strain. In this study, we collected serum and peripheral blood mononuclear cells (PBMCs) from 57 study participants of median 35-year old's working in the health care field, who have received different vaccination regimens. Neutralization assays revealed robust but decreased neutralization of Omicron VOC, including BA.1 and BA.4/5, compared to WT SARS-CoV-2 in all vaccine groups and increased WT SARS-CoV-2 binding and neutralizing antibodies titers in homologous mRNA prime-boost-boost study participants. By investigating cytokine production, we found that homologous and heterologous prime-boost-boost-vaccination induces a robust cytokine response of CD4+ and CD8+ T cells. Collectively, our results indicate robust humoral and T cell mediated immunity against Omicron in homologous and heterologous prime-boost-boost vaccinated study participants, which might serve as a guide for policy decisions.

A Central Role for Atg5 in Microbiota-Dependent Foxp3+ RORγt+ Treg Cell Preservation to Maintain Intestinal Immune Homeostasis.

Autophagy is an evolutionary conserved catabolic pathway that ensures the degradation of intracellular components. The autophagic pathway is regulated by autophagy-related (Atg) proteins that govern formation of double-membraned vesicles called autophagosomes. Autophagy deficiency in regulatory T (Treg) cells leads to increased apoptosis of these cells and to the development of autoimmune disorders, predominantly characterized by intestinal inflammation. Recently, RORγt-expressing Treg cells have been identified as key regulators of gut homeostasis, preventing intestinal immunopathology. To study the role of autophagy in RORγt+ Foxp3+ Treg cells, we generated mice lacking the essential component of the core autophagy machinery Atg5 in Foxp3+ cells. Atg5 deficiency in Treg cells led to a predominant intestinal inflammation. While Atg5-deficient Treg cells were reduced in peripheral lymphoid organs, the intestinal RORγt+ Foxp3+ subpopulation of Treg cells was most severely affected. Our data indicated that autophagy is essential to maintain the intestinal RORγt+ Foxp3+ Treg population, thereby protecting the mice from gut inflammatory disorders.

Novel Insights into YB-1 Signaling and Cell Death Decisions.

YB-1 belongs to the evolutionarily conserved cold-shock domain protein family of RNA binding proteins. YB-1 is a well-known transcriptional and translational regulator, involved in cell cycle progression, DNA damage repair, RNA splicing, and stress responses. Cell stress occurs in many forms, e.g., radiation, hyperthermia, lipopolysaccharide (LPS) produced by bacteria, and interferons released in response to viral infection. Binding of the latter factors to their receptors induces kinase activation, which results in the phosphorylation of YB-1. These pathways also activate the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a well-known transcription factor. NF-κB is upregulated following cellular stress and orchestrates inflammatory responses, cell proliferation, and differentiation. Inflammation and cancer are known to share common mechanisms, such as the recruitment of infiltrating macrophages and development of an inflammatory microenvironment. Several recent papers elaborate the role of YB-1 in activating NF-κB and signaling cell survival. Depleting YB-1 may tip the balance from survival to enhanced apoptosis. Therefore, strategies that target YB-1 might be a viable therapeutic option to treat inflammatory diseases and improve tumor therapy.

Autophagy-A Story of Bacteria Interfering with the Host Cell Degradation Machinery.

Autophagy is a highly conserved and fundamental cellular process to maintain cellular homeostasis through recycling of defective organelles or proteins. In a response to intracellular pathogens, autophagy further acts as an innate immune response mechanism to eliminate pathogens. This review will discuss recent findings on autophagy as a reaction to intracellular pathogens, such as Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, and pathogenic Escherichia coli. Interestingly, while some of these bacteria have developed methods to use autophagy for their own benefit within the cell, others have developed fascinating mechanisms to evade recognition, to subvert the autophagic pathway, or to escape from autophagy.

Regulating T-cell differentiation through the polyamine spermidine.

BACKGROUND: The cross-talk between the host and its microbiota plays a key role in the promotion of health. The production of metabolites such as polyamines by intestinal-resident bacteria is part of this symbiosis shaping host immunity. The polyamines putrescine, spermine, and spermidine are abundant within the gastrointestinal tract and might substantially contribute to gut immunity. OBJECTIVE: We aimed to characterize the polyamine spermidine as a modulator of T-cell differentiation and function. METHODS: Naive T cells were isolated from wild-type mice or cord blood from healthy donors and submitted to polarizing cytokines, with and without spermidine treatment, to evaluate CD4+ T-cell differentiation in vitro. Moreover, mice were subjected to oral supplementation of spermidine, or its precursor l-arginine, to assess the frequency and total numbers of regulatory T (Treg) cells in vivo. RESULTS: Spermidine modulates CD4+ T-cell differentiation in vitro, preferentially committing naive T cells to a regulatory phenotype. After spermidine treatment, activated T cells lacking the autophagy gene Atg5 fail to upregulate Foxp3 to the same extent as wild-type cells. These results indicate that spermidine's polarizing effect requires an intact autophagic machinery. Furthermore, dietary supplementation with spermidine promotes homeostatic differentiation of Treg cells within the gut and reduces pathology in a model of T-cell transfer-induced colitis. CONCLUSION: Altogether, our results highlight the beneficial effects of spermidine, or l-arginine, on gut immunity by promoting Treg cell development.

YB-1 Mediates TNF-Induced Pro-Survival Signaling by Regulating NF-κB Activation.

Cell fate decisions regulating survival and death are essential for maintaining tissue homeostasis; dysregulation thereof can lead to tumor development. In some cases, survival and death are triggered by the same receptor, e.g., tumor necrosis factor (TNF)-receptor 1 (TNFR1). We identified a prominent role for the cold shock Y-box binding protein-1 (YB-1) in the TNF-induced activation and nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65. In the absence of YB-1, the expression of TNF receptor-associated factor 2 (TRAF2), a central component of the TNF receptor signaling complex required for NF-κB activation, is significantly reduced. Therefore, we hypothesized that the loss of YB-1 results in a destabilization of TRAF2. Consistent with this hypothesis, we observed that YB-1-deficient cells were more prone to TNF-induced apoptotic cell death. We observed enhanced effector caspase-3 activation and could successfully rescue the cells using the pan-caspase inhibitor zVAD-fmk, but not necrostatin-1. Taken together, our results indicate that YB-1 plays a central role in promoting cell survival through NF-κB activation and identifies a novel mechanism by which enhanced YB-1 expression may contribute to tumor development.